Hi Elias, GameBoy used to come with a low resolution(16x16 I think) chip which they called "Artificial Retina". It was (may be it still is!) popular among robot enthusiasts. These chips used to come for auction at ebay and some of my friends bought dozens at a time, because they were inexpensive. Try searching for Artificial Retina on the web. As for tilt sensor, electrolytic tilt sensors are fairly cheap(5 to 8$). Buy the tilt sensor alone and supply pure ac signal(no dc!) using a function generator chip like the XR2206(+/-5V). Electronics is straight forward for simple applications. Best of luck! Vetri -----Original Message----- From: pic microcontroller discussion list [mailto:PICLIST@MITVMA.MIT.EDU] On Behalf Of Elias Nakos Sent: Friday, December 05, 2003 3:02 PM To: PICLIST@MITVMA.MIT.EDU Subject: [PIC:]Sensors for Mobile Robots Hi all, I am an master student in robotics and automation, and I am building a hexapod robot for my dissertation. Could you please give me any information about sensors available for mobile robots especially legged ones. I know that there's a book around but I can't afford it. So is there anyone kind enough to tell me what sensors i could use and brief information on how to interface them (h/w & s/w interface) with 16f877 or at least any web site giving such informations. The ones that I am currently using are simple IR photodiodes (18 to 20 degrees) for object recognition, photoresistors (LDRs), ultrasonic and I am bit confused about the type of contact sensors I could use. A web site would be enough, but could u propose a type of contact sensors and especially a good Tilt or INCLINATION sensor. i am currently using a tilt switch which is off at 90 degrees. Imagine the robot to get an inclination of 90 degrees until the switch goes off!!!! I guess there's no coming back from that state. Anyway any help would be great. Thank you guys. yours, Elias Nakos -- http://www.piclist.com hint: The PICList is archived three different ways. See http://www.piclist.com/#archives for details. -- http://www.piclist.com hint: The PICList is archived three different ways. See http://www.piclist.com/#archives for details.